P21AB

Reductant Level Sensor B Circuit High

Severity

⚠️ Medium

Can you drive?

Yes, but get it checked soon

Approx. repair cost

$33–89 (est.)

Symptoms

Check Engine light comes on
Reduced efficiency of the SCR system
Possible engine power restrictions
Low reagent level message may not display correctly
Increased NOx emissions

Causes

Reagent B level sensor malfunction
Short circuit in the sensor circuit
Broken or damaged wiring
Problems with sensor connectors
SCR control module malfunction

How to Fix

Check the level and quality of the reagent (AdBlue)
Visually inspect the sensor wiring and connectors
Check the resistance and voltage in the sensor circuit
Replace the reagent level sensor if necessary
Test the operation of the SCR control module

Related codes

P21AA P21AC P21AD